FWIW, that design ammo box and label is the earliest Remington-U.M.C. type, and dates from between 1911 and 1915.

And technically, it was U.M.C. (more specifically, Marcellus Hartley) that acquired Remington Arms Co. in 1888, the merger of the two companies into Remington Arms - U.M.C.Co. occurring in 1912.